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ac24299636
The `mir!` macro has multiple parts:
- An optional return type annotation.
- A sequence of zero or more local declarations.
- A mandatory starting anonymous basic block, which is brace-delimited.
- A sequence of zero of more additional named basic blocks.
Some `mir!` invocations use braces with a "block" style, like so:
```
mir! {
let _unit: ();
{
let non_copy = S(42);
let ptr = std::ptr::addr_of_mut!(non_copy);
// Inside `callee`, the first argument and `*ptr` are basically
// aliasing places!
Call(_unit = callee(Move(*ptr), ptr), ReturnTo(after_call), UnwindContinue())
}
after_call = {
Return()
}
}
```
Some invocations use parens with a "block" style, like so:
```
mir!(
let x: [i32; 2];
let one: i32;
{
x = [42, 43];
one = 1;
x = [one, 2];
RET = Move(x);
Return()
}
)
```
And some invocations uses parens with a "tighter" style, like so:
```
mir!({
SetDiscriminant(*b, 0);
Return()
})
```
This last style is generally used for cases where just the mandatory
starting basic block is present. Its braces are placed next to the
parens.
This commit changes all `mir!` invocations to use braces with a "block"
style. Why?
- Consistency is good.
- The contents of the invocation is a block of code, so it's odd to use
parens. They are more normally used for function-like macros.
- Most importantly, the next commit will enable rustfmt for
`tests/mir-opt/`. rustfmt is more aggressive about formatting macros
that use parens than macros that use braces. Without this commit's
changes, rustfmt would break a couple of `mir!` macro invocations that
use braces within `tests/mir-opt` by inserting an extraneous comma.
E.g.:
```
mir!(type RET = (i32, bool);, { // extraneous comma after ';'
RET.0 = 1;
RET.1 = true;
Return()
})
```
Switching those `mir!` invocations to use braces avoids that problem,
resulting in this, which is nicer to read as well as being valid
syntax:
```
mir! {
type RET = (i32, bool);
{
RET.0 = 1;
RET.1 = true;
Return()
}
}
```
79 lines
1.6 KiB
Rust
79 lines
1.6 KiB
Rust
// `SetDiscriminant` does not actually write anything if the chosen variant is the untagged variant
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// of a niche encoding. Verify that we do not thread over this case.
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//@ test-mir-pass: JumpThreading
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#![feature(custom_mir)]
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#![feature(core_intrinsics)]
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use std::intrinsics::mir::*;
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enum E<T> {
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A,
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B(T),
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}
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// EMIT_MIR set_no_discriminant.f.JumpThreading.diff
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#[custom_mir(dialect = "runtime")]
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pub fn f() -> usize {
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// CHECK-LABEL: fn f(
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// CHECK-NOT: goto
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// CHECK: switchInt(
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// CHECK-NOT: goto
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mir! {
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let a: isize;
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let e: E<char>;
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{
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e = E::A;
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SetDiscriminant(e, 1);
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a = Discriminant(e);
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match a {
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0 => bb0,
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_ => bb1,
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}
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}
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bb0 = {
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RET = 0;
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Return()
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}
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bb1 = {
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RET = 1;
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Return()
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}
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}
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}
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// EMIT_MIR set_no_discriminant.generic.JumpThreading.diff
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#[custom_mir(dialect = "runtime")]
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pub fn generic<T>() -> usize {
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// CHECK-LABEL: fn generic(
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// CHECK-NOT: goto
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// CHECK: switchInt(
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// CHECK-NOT: goto
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mir! {
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let a: isize;
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let e: E<T>;
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{
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e = E::A;
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SetDiscriminant(e, 1);
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a = Discriminant(e);
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match a {
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0 => bb0,
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_ => bb1,
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}
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}
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bb0 = {
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RET = 0;
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Return()
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}
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bb1 = {
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RET = 1;
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Return()
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}
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}
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}
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fn main() {
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assert_eq!(f(), 0);
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assert_eq!(generic::<char>(), 0);
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}
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